Method and system for controlling and monitoring an array of point-of-load regulators

ABSTRACT

A power control system comprises a plurality of POL regulators, at least one serial data bus operatively connecting the plurality of POL regulators, and a system controller connected to the serial data bus and adapted to send and receive digital data to and from the plurality of POL regulators. The serial data bus further comprises a first data bus carrying programming and control information between the system controller and the plurality of POL regulators. The serial data bus may also include a second data bus carrying fault management information between the system controller and the plurality of POL regulators. The power control may also include a front-end regulator providing an intermediate voltage to the plurality of POL regulators on an intermediate voltage bus.

RELATED APPLICATION DATA

This patent application is a continuation of U.S. patent applicationSer. No. 11/165,798, filed Jun. 24, 2005, issued as U.S. Pat. No.7,456,617 on Nov. 25, 2008, which is a continuation-in-part of U.S.patent application Ser. No. 10/326,222, filed Dec. 21, 2002, issued asU.S. Pat. No. 7,000,125 on Feb. 14, 2006 and U.S. patent applicationSer. No. 10/293,001, filed Nov. 13, 2002, issued as U.S. Pat. No.7,049,798 on May 23, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to power control systems, or moreparticularly, to a method and system to control and monitor an array ofpoint-of-load regulators.

2. Description of Related Art

With the increasing complexity of electronic systems, it is common foran electronic system to require power provided at several differentdiscrete voltage and current levels. For example, electronic systems mayinclude discrete circuits that require voltages such as 3v, 5v, 9v, etc.Further, many of these circuits require a relatively low voltage (e.g.,1v), but with relatively high current (e.g., 100A). It is undesirable todeliver relatively high current at low voltages over a relatively longdistance through an electronic device for a number of reasons. First,the relatively long physical run of low voltage, high current linesconsumes significant circuit board area and congests the routing ofsignal lines on the circuit board. Second, the impedance of the linescarrying the high current tends to dissipate a lot of power andcomplicate load regulation. Third, it is difficult to tailor thevoltage/current characteristics to accommodate changes in loadrequirements.

In order to satisfy these power requirements, it is known to distributean intermediate bus voltage throughout the electronic system, andinclude an individual point-of-load (“POL”) regulator, i.e., DC/DCconverter, at the point of power consumption within the electronicsystem. Particularly, a POL regulator would be included with eachrespective electronic circuit to convert the intermediate bus voltage tothe level required by the electronic circuit. An electronic system mayinclude multiple POL regulators to convert the intermediate bus voltageinto each of the multiple voltage levels. Ideally, the POL regulatorwould be physically located adjacent to the corresponding electroniccircuit so as to minimize the length of the low voltage, high currentlines through the electronic system. The intermediate bus voltage can bedelivered to the multiple POL regulators using low current lines thatminimize loss.

With this distributed approach, there is a need to coordinate thecontrol and monitoring of the POL regulators of the power system. ThePOL regulators generally operate in conjunction with a power supplycontroller that activates, programs, and monitors the individual POLregulators. It is known in the art for the controller to use amulti-connection parallel bus to activate and program each POLregulator. For example, the parallel bus may communicate anenable/disable bit for turning each POL regulator on and off, andvoltage identification (VID) code bits for programming the outputvoltage set-point of the POL regulators. The controller may further useadditional connections to monitor the voltage/current that is deliveredby each POL regulator so as to detect fault conditions of the POLregulators. A drawback with such a control system is that it addscomplexity and size to the overall electronic system.

Thus, it would be advantageous to have a system and method forcontrolling and monitoring POL regulators within a distributed powersystem.

SUMMARY OF THE INVENTION

The present invention provides a system and method for controlling andmonitoring POL regulators within a distributed power system.

In an embodiment of the invention, the power control system comprises aplurality of POL regulators, at least one serial data bus operativelyconnecting the plurality of POL regulators, and a system controllerconnected to the serial data bus and adapted to send and receive digitaldata to and from the plurality of POL regulators. The serial data busfurther comprises a first data bus carrying programming, control andmonitoring information between the system controller and the pluralityof POL regulators. The serial data bus may also include a second databus carrying fault management information between the system controllerand the plurality of POL regulators. The power control may also includea front-end regulator providing an intermediate voltage to the pluralityof POL regulators on an intermediate voltage bus.

The POL control system enables four different modes of operation. In thefirst operational mode, the POL regulators function independently in theabsence of a system controller and without interaction with other POLregulators. In the second operational mode, the POL regulatorsinteroperate for the purpose of current sharing or interleaving in theabsence of a system controller. In the third operational mode, the POLregulators operate as an array in which the behavior of each POLregulator and the array as a whole are coordinated by a systemcontroller. Lastly, the fourth operational mode includes both centralcontrol using the system controller and local control over certainfunctionality. This way, the POL regulators operate as an arraycoordinated by a system controller and also interoperate with each otherto perform functions such as current sharing.

A more complete understanding of the method and system for controllingand monitoring a plurality of POL regulators will be afforded to thoseskilled in the art, as well as a realization of additional advantagesand objects thereof, by a consideration of the following detaileddescription of the preferred embodiment. Reference will be made to theappended sheets of drawings, which will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a prior art distributed power delivery system;

FIG. 2 depicts a prior art POL control system using a parallel controlbus;

FIG. 3 depicts an exemplary POL control system constructed in accordancewith an embodiment of the present invention;

FIG. 4 depicts an exemplary POL regulator of the POL control system;

FIG. 5 depicts an exemplary system controller of the POL control system;

FIG. 6 depicts an exemplary method of communicating with a POL regulatorover a serial bus;

FIG. 7 depicts an exemplary method of providing/utilizingfault-monitoring data in a POL control system;

FIG. 8 depicts an exemplary communication cycle that may be transmittedto/from a POL regulator;

FIG. 9 depicts an alternative embodiment of a POL control system;

FIG. 10 depicts another alternative embodiment of a POL control system;

FIG. 11 depicts an exemplary method for programming parameters foroperating a POL control system; and

FIGS. 12A-12D depict an exemplary POL control system being programmed inaccordance with the method of FIG. 11;

FIG. 13 depicts an exemplary communication cycle for transmittinginformation to/from a POL regulator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a system and method for controlling andmonitoring POL regulators within a distributed power system. In thedetailed description that follows, like element numerals are used todescribe like elements illustrated in one or more figures.

Referring first to FIG. 1, a prior art distributed power delivery systemis shown. The prior art distributed power deliver system includes anAC/DC converter 12 that converts the available AC power into a primaryDC power source, e.g., 48 volts. The primary DC power source isconnected to a primary power bus that distributes DC power to pluralelectronic systems, such as printed circuit board 14. The bus may befurther coupled to a battery 18 providing a back-up power source for theelectronic systems connected to the primary power bus. When the AC/DCconverter 12 is delivering DC power into the primary power bus, thebattery 18 is maintained in a fully charged state. In the event of lossof AC power or fault with the AC/DC converter 12, the battery 18 willcontinue to deliver DC power to the primary power bus for a limitedperiod of time defined by the capacity of the battery 18.

The printed circuit board 14 may further include a DC/DC converter thatreduces the primary bus voltage to an intermediate voltage level, suchas 5 or 12 volts. The intermediate voltage is then distributed over anintermediate power bus provided to plural circuits on the printedcircuit board 14. Each circuit has an associated point-of-load (“POL”)regulator located closely thereby, such as POLs 22, 24, and 26. Each POLregulator converts the intermediate bus voltage to a low voltage, highcurrent level demanded by the electronic circuit, such as 1.8 volts, 2.5volts, and 3.3 volts provided by POLs 22, 24, and 26, respectively. Itshould be appreciated that the voltage levels described herein areentirely exemplary, and that other voltage levels could be selected tosuit the particular needs of electronic circuits on the printed circuitboard 14. By locating the POLs 22, 24, 26 close to their correspondingelectronic circuits, the length of the low voltage, high current lineson the printed circuit board 14 are minimized. Moreover, theintermediate power bus can be adapted to carry relatively low current,thereby minimizing power loss due to the line impedance. But, thisdistributed power delivery system does not provide a way to monitor andcontrol the performance of the POLs 22, 24, 26.

FIG. 2 illustrates a prior art DC/DC converter control system having apower supply controller 32 and a plurality of DC/DC converters 34, 36,38, and 42. The DC/DC converters 34, 36, 38, and 42 are each connectedto a power bus (as described above with respect to FIG. 1), whichprovides an input voltage. The DC/DC converters 34, 36, 38, and 42 eachprovide a low voltage, high current output that passes throughrespective sensing resistors 46, 52, 56, and 62 and respective switches48, 54, 58, and 64. The controller 32 provides control signals to theDC/DC converters 34, 36, 38, and 42 via a plurality of six-bit parallelbuses that each carry an enable/disable bit and five VID code bits. TheVID code bits program the DC/DC converters for a desired outputvoltage/current level. The controller 32 also monitors the performanceof the DC/DC converters 34, 36, 38, and 42 using the sensing resistors46, 52, 56, and 62. Particularly, the controller 32 monitors the outputvoltage of each DC/DC converter by detecting the voltage at the outputside of the sensing resistor, and monitors the output current throughthe sensing resistor by detecting the voltage across the sensingresistor. The voltage and current sensing for each DC/DC converterrequires two separate lines, so eight separate lines are needed to sensethe voltage and current condition of the exemplary four-convertersystem. Moreover, the controller 32 has a switch enable line connectedto the gate terminals of switches 48, 54, 58, and 64, by which thecontroller 32 can shut off the output from any of the DC/DC controllers34, 36, 38, and 42.

In an exemplary operation, the controller 32 provides control parameters(e.g., output voltage set-point) to the DC/DC converter 34 via the VIDcode portion of the six-bit parallel bus. The controller 32 thenactivates the DC/DC converter 34 via the enable/disable portion of thesix-bit parallel bus. Once activated, the DC/DC converter 34 convertsthe power bus voltage (e.g., 48 volts) into a selected output voltage.The controller 32 then verifies that the output voltage is the desiredvoltage by measuring the voltage via the voltage monitoring line. If theoutput voltage is within an acceptable range, it is provided to the load(not shown) by activating the switch 48 via the switch enable line. Thecontroller 32 can then continuously monitor the output voltage and theoutput current produced by the DC/DC converter 34 by measuring theoutput voltage via the voltage monitoring line and measuring the voltagedrop across the sensing resistor (i.e., the voltage differential betweenthe current monitoring line and the voltage monitoring line). If thecontroller 32 detects a fault condition of the DC/DC converter 34 (e.g.,output voltage drops below a specific threshold), the controller 32 candisable and reset the DC/DC converter. The controller 32 communicateswith the other DC/DC converters 36, 38, and 42 in the same manner.

A disadvantage with the control system of FIG. 2 is that it addscomplexity and size to the overall electronic system by using a six-bitparallel bus to control each DC/DC converter and a separate three-lineoutput connection to monitor the performance of each DC/DC converter. Inother words, the controller 32 utilizes thirty-six separate connectionsin order to communicate with four DC/DC converters 34, 36, 38, and 42.As the complexity and power requirements of electronic systems increase,the number of connections to the controller will also increase in alinear manner.

Referring now to FIG. 3, a POL control system 100 is shown in accordancewith an embodiment of the present invention. Specifically, the POLcontrol system 100 includes a system controller 102, a front-endregulator 104, and a plurality of POL regulators 106, 108, 110, 112, and114 arranged in an array. The POL regulators depicted herein include,but are not limited to, point-of-load regulators, power-on-loadregulators, DC/DC converters, voltage regulators, and all otherprogrammable voltage or current regulating devices generally known tothose skilled in the art. An intra-device interface is provided betweenindividual ones of the POL regulators to control specific interactions,such as current share or paralleling, e.g., current share interface(CS1) provided between POL0 106 and POL1 108, and CS2 provided betweenPOL4 112 and POLn 114. In the exemplary configuration shown in FIG. 3,POL0 106 and POL1 108 operate in parallel mode to produce output voltageV_(O1) with increased current capability, POL2 110 produces outputvoltage V_(O2), and POL4 112 and POLn 114 operate in parallel mode toproduce output voltage V_(O3), though it should be appreciate that othercombinations and other numbers of POL regulators could be advantageouslyutilized.

The front-end regulator 104 provides an intermediate voltage to theplurality of POL regulators over an intermediate voltage bus, and maysimply comprise another POL regulator. The system controller 102 andfront-end regulator 104 may be integrated together in a single unit, ormay be provided as separate devices. Alternatively, the front-endregulator 104 may provide a plurality of intermediate voltages to thePOL regulators over a plurality of intermediate voltage buses. Thesystem controller 102 may draw its power from the intermediate voltagebus.

The system controller 102 communicates with the plurality of POLregulators by writing and/or reading digital data (either synchronouslyor asynchronous) via a uni-directional or bi-directional serial bus,illustrated in FIG. 3 as the synch/data bus. The synch/data bus maycomprise a two-wire serial bus (e.g., I²C) that allows data to betransmitted asynchronously or a single-wire serial bus that allows datato be transmitted synchronously (i.e., synchronized to a clock signal).In order to address any specific POL in the array, each POL isidentified with a unique address, which may be hardwired into the POL orset by other methods. The system controller 102 also communicates withthe plurality of POL regulators for fault management over a seconduni-directional or bi-directional serial bus, illustrated in FIG. 3 asthe OK/fault bus. By grouping plural POL regulators together byconnecting them to a common OK/fault bus allows the POL regulators havethe same behavior in the case of a fault condition. Also, the systemcontroller 102 communicates with a user system via a user interface busfor programming, setting, and monitoring of the POL control system 10.Lastly, the system controller 102 communicates with the front-endregulator 104 over a separate line to disable operation of the front-endregulator.

An exemplary POL regulator 106 of the POL control system 10 isillustrated in greater detail in FIG. 4. The other POL regulators ofFIG. 3 have substantially identical configuration. The POL regulator 106includes a power conversion circuit 142, a serial interface 144, a POLcontroller 146, default configuration memory 148, and hardwired settingsinterface 150. The power conversion circuit 142 transforms an inputvoltage (V_(i)) to the desired output voltage (V_(O)) according tosettings received through the serial interface 144, the hardwiredsettings 150 or default settings. The power conversion circuit 142 mayalso include monitoring sensors for output voltage, current, temperatureand other parameters that are used for local control and alsocommunicated back to the system controller through the serial interface144. The power conversion circuit 142 may also generate a Power Good(PG) output signal for stand-alone applications in order to provide asimplified monitoring function. The serial interface 144 receives andsends commands and messages to the system controller 102 via thesynch/data and OK/fault serial buses. The default configuration memory148 stores the default configuration for the POL regulator 106 in caseswhere no programming signals are received through the serial interface144 or hardwired settings interface 150. The default configuration isselected such that the POL regulator 106 will operate in a “safe”condition in the absence of programming signals.

The hardwired settings interface 150 communicates with externalconnections to program the POL regulator without using the serialinterface 144. The hardwired settings interface 150 may include asinputs the address setting (Addr) of the POL to alter or set some of thesettings as a function of the address (i.e., the identifier or the POL),e.g., phase displacement, enable/disable bit (En), trim., and VID codebits. Further, the address identifies the POL regulator duringcommunication operations through the serial interface 144. The triminput allows the connection of one or more external resistors to definean output voltage level for the POL regulator. Similarly, the VID codebits can be used to program the POL regulator for a desired outputvoltage/current level. The enable/disable bit allows the POL regulatorto be turned on/off by toggling a digital high/low signal.

The POL controller 146 receives and prioritizes the settings of the POLregulator. If no settings information is received via either thehardwired settings interface 150 or the serial interface 144, the POLcontroller 146 accesses the parameters stored in the defaultconfiguration memory 148. Alternatively, if settings information isreceived via the hardwired settings interface 150, then the POLcontroller 146 will apply those parameters. Thus, the default settingsapply to all of the parameters that cannot be or are not set throughhard wiring. The settings received by the hardwired settings interface150 can be overwritten by information received via the serial interface144. The POL regulator can therefore operate in a stand-alone mode, afully programmable mode, or a combination thereof. This programmingflexibility enables a plurality of different power applications to besatisfied with a single generic POL regulator, thereby reducing the costand simplifying the manufacture of POL regulators.

An exemplary system controller 102 of the POL control system 100 isillustrated in FIG. 5. The system controller 102 includes a userinterface 122, a POL interface 124, a controller 126, and a memory 128.The user interface 122 sends and receives messages to/from the user viathe user interface bus. The user interface bus may be provided by aserial or parallel bi-directional interface using standard interfaceprotocols, e.g., an I²C interface. User information such as monitoringvalues or new system settings would be transmitted through the userinterface 122. The POL interface 124 transforms data to/from the POLregulators via the synch/data and OK/fault serial buses. The POLinterface 124 communicates over the synch/data serial bus to transmitsetting data and receive monitoring data, and communicates over theOK/fault serial bus to receive interrupt signals indicating a faultcondition in at least one of the connected POL regulators. The memory128 comprises a non-volatile memory storage device used to store thesystem set-up parameters (e.g., output voltage, current limitationset-point, timing data, etc.) for the POL regulators connected to thesystem controller 102. Optionally, a secondary, external memory 132 mayalso be connected to the user interface 122 to provide increased memorycapacity for monitoring data or setting data.

The controller 126 is operably connected to the user interface 122, thePOL interface 124, and the memory 128. The controller 126 has anexternal port for communication a disable signal (FE DIS) to thefront-end regulator 104. At start-up of the POL control system 100, thecontroller 126 reads from the internal memory 128 (and/or the externalmemory 132) the system settings and programs the POL regulatorsaccordingly via the POL interface 124. Each of the POL regulators isthen set up and started in a prescribed manner based on the systemprogramming. During normal operation, the controller 126 decodes andexecutes any command or message coming from the user or the POLregulators. The controller 126 monitors the performance of the POLregulators and reports this information back to the user through theuser interface 122. The POL regulators may also be programmed by theuser through the controller 126 to execute specific, autonomousreactions to faults, such as over current or over voltage conditions.Alternatively, the POL regulators may be programmed to only report faultconditions to the system controller 102, which will then determine theappropriate corrective action in accordance with predefined settings,e.g., shut down the front-end regulator via the FE DIS control line.

A monitoring block 130 may optionally be provided to monitor the stateof one or more voltage or current levels of other power systems notoperably connected to the controller 102 via the synch/data or OK/faultbuses. The monitoring block 130 may provide this information to thecontroller 126 for reporting to the user through the user interface inthe same manner as other information concerning the POL control system10. This way, the POL control system 10 can provide some backwardcompatibility with power systems that are already present in anelectronic system.

Returning to FIG. 3, the system controller 102 is adapted to provideinitial-configuration data to each POL regulator (i.e., 106, 108, 110,112, 114). It should be appreciated that the initial-configuration datamay include, but is not limited to, one or more of the following typesof data: output-voltage-set-point-data (i.e., a desired output voltage);output-current-set-point data (i.e., the highest desired outputcurrent); low-voltage-limit data (i.e., the lowest desired outputvoltage); high-voltage-limit data (i.e., the highest desired outputvoltage); output-voltage-slew-rate data (i.e., the desired output slewrate); enable/disable data (i.e., turning on/off the POL regulatoroutput); timing data (e.g., turn-on delay, turn-off delay, faultrecovery time, etc.) and/or all other types of POL programming datagenerally known to those skilled in the art. Once theinitial-configuration data is received, the POL controller 146 (see FIG.4) is adapted to store at least a portion of the initial-configurationdata in memory. At least a portion of the stored initial-configurationdata is then used to produce a desired output. For example, an outputmay be produced to include a particular voltage level, a particular slewrate, etc., depending on the type of initial-configuration datareceived/stored.

After the output has been produced, the POL controller 146 is adapted toreceive fault-monitoring data (e.g., from an external device, a sensecircuit, etc.). The fault-monitoring data, which contains information onthe POL regulator or its output, is then stored in the memory. The POLcontroller 146, in response to a condition (e.g., receiving a request,exceeding a known parameter, having a register's contents change, etc.),is then adapted to provide at least a portion of the fault-monitoringdata to the system controller 102. It should be appreciated that thefault-monitoring data may include, but is not limited to, one or more ofthe following types of data: output-voltage data, which may includeactual-output-voltage data (i.e., the measured output voltage) orvoltage-comparison data (e.g., whether the measured output voltage isabove or below the highest desired output voltage, whether the measuredoutput voltage is above or below the lowest desired output voltage,etc.); output-current data, which may include actual-output-current data(i.e., the measured output current) or current-comparison data (e.g.,whether the measured output current is above or below the highestdesired output current); temperature-status data, which may includeactual-temperature data (i.e., the measured temperature of a POLregulator, or more particularly its heat generating components) ortemperature-comparison data (e.g., whether the temperature of the POLregulator (or its components) is above or below a known value, etc.),and/or all other types of POL fault monitoring data generally known tothose skilled in the art. It should also be appreciated thatfault-monitoring data is not limited to data representing the existenceof a faulty condition. For example, fault-monitoring data that indicatesthat the POL regulator is operating within acceptable parameters (e.g.,within an acceptable temperature range) is considered to be within thespirit and scope of the present invention.

The fault-monitoring data can be used by either the system controller102 or the POL controller 146 to monitor and/or control the POLregulator. In other words, the POL controller 146 can use thefault-monitoring data to either provide POL status information (i.e.,data corresponding to a particular POL regulator or its output) to thesystem controller 102 or disable the POL regulator if a particularcondition is met (e.g., the status register changes, the temperaturelimit has been exceeded, etc.). Alternatively, the system controller 102can use the fault-monitoring data to either provide POL statusinformation to an administrator, disable a particular POL regulator, orstore the fault-monitoring data for future use. For example, in oneembodiment of the present invention, each POL regulator includes uniqueID data (e.g., serial number, date of manufacture, etc.) stored in an IDregister. This enables the system controller 102 to provide POL statusinformation and unique ID data to an administrator.

In another embodiment of the present invention, each POL regulatorfurther includes at least one sensor circuit. The sensor circuit is usedto produce either the fault-monitoring data, or data that can be used(e.g., together with information stored in the memory) to produce thefault-monitoring data. It should be appreciated that the sensor circuit,as described herein, will vary (e.g., as to circuitry, location, inputs,etc.) depending upon the type of information that is being detected. Forexample, a sensor circuit that detects current may include differentcircuitry, have different inputs, and be placed in a different locationthan a sensor circuit that detects temperature.

FIG. 8 illustrates a signal adapted to be communicated over thesynch/data bus. Specifically, a transmission line is created bypropagating a clock signal 800 over the bus. The clock signal 800 can begenerated by the system controller 102, a particular POL regulator(e.g., the POL regulator with the least significant address), or anexternal device. The clock signal 800 synchronizes the variouscommunicating devices (i.e., the POL regulators and the controller) andcreates a series of clock cycles 810, each one including at least onedata bit. This allows the various communicating devices to transmit asingle bit of data for every clock cycle 810. In other words, eachcommunicating device transmits data by leaving/pulling the data bit highor low (i.e., binary one or zero).

FIG. 13 illustrates an exemplary communication cycle 50 for transmittinginformation between the system controller 102 and at least one POLregulator. Specifically, the communication cycle 50 can be used totransmit initial-configuration data, fault-monitoring data, unique IDdata, or any other type of data. As shown in FIG. 13, an exemplaryforty-two bit transmission cycle 50 includes a start sequence 510 (e.g.,four bits), an address 520, a command set 530, a first acknowledgementbit 540, a data set 560, and a second acknowledge bit 570. An additionalbit 550 has been added to ensure that the command set 540 is executedbefore the data set 560 is provided.

The first and second acknowledgement bits 540, 570 are used toacknowledge the reception of the command set 530 and the data set 560,respectively. It should be appreciated that the device responsible forthe providing the first and second acknowledgement bits 540, 570 variesdepending upon whether the information is being sent to or from the POLregulator (i.e., whether the information is being written, read, orprovided).

The command set 530, data set 560, and address set 520 enable the systemcontroller 102 and the POL regulators to write, read and provide data.Specifically, (i) the command set 530 is used to identify whether andwhat the controller is writing (e.g., writing to the status register),the controller is reading (e.g., reading the status register), or thePOL regulator is providing (e.g., providing status registerinformation), (ii) the address set 520 is used to identify the POLregulator(s) that is being written to or read, or the POL regulator thatis providing information, and (iii) the data set 560 is used to identifythe actual data that is being written, read, or provided.

The start sequence 510 and address set 520 are used, in part, toidentify the sender of the information. For example, the systemcontroller 102 may use a different start sequence 510 than theindividual POL regulators. Thus, the system controller 102 candetermine, by reading the start sequence 510 of the communication cycle50 being transmitted, whether a POL regulator is also attempting to senda communication cycle 50 at the same time. Similarly, each POL regulatormay have a different address set 520. Thus, a POL regulator candetermine, by reading the start sequence 510 and address set 520 of thecommunication cycle 50 being transmitted, whether another POL regulatoror the controller is also attempting to send a communication cycle 50 atthe same time. If multiple devices are attempting to send acommunication cycle 50, sequencing data is used to allocate or arbitratebus use. It should be appreciated that the sequence data can either bestored (or hard wired) as a default value or provided asinitial-configuration data and stored in the storage device (e.g., asequencing configuration register).

One method of providing/utilizing initial-communication data isillustrated in FIG. 6, starting at step 610. Specifically, at step 620,the POL control unit begins by receiving initial-configuration data(e.g., output-voltage-set-point, output-current-set-point, etc.). Theinitial-configuration data is then stored in memory at step 630. At step640, the POL control unit uses at least a portion of theinitial-configuration data to determine at least one output parameter(e.g., voltage level, slew rate, etc.) of the POL regulator. The POLcontrol unit then generates an output including the output parameter(s)at step 650, ending the process at step 660.

One method of providing/utilizing fault-monitoring data is illustratedin FIG. 7, starting at step 710. Specifically, at step 720, the POLregulator, or more particularly a sensor circuit (either alone ortogether with information stored in the storage device) detectsfault-monitoring data (e.g., output-voltage data, output-current data,etc.). The fault-monitoring data is then stored in memory at step 730.At step 740, the system controller 102 sends (and the POL controller 146receives) a request for at least a portion of the fault-monitoring data.At step 750, the POL controller 146 provides the requested portion ofthe fault-monitoring data to the system controller 102. The systemcontroller 102, at step 760, uses the requested portion of thefault-monitoring data to monitor at least one parameter of the POLregulator.

At step 770, the system controller 102 determines whether the monitoredparameter violates a known parameter. For example, if the monitoredparameter is output voltage, the output voltage could be compared to amaximum output voltage value. If a violation occurs (e.g., the outputvoltage exceeds a maximum output voltage value), then the POL regulatorwould be disabled at step 780. Alternatively, if a violation does notoccur, the system controller 102 continues monitoring the POL regulatorby again requesting at least a portion of fault-monitoring data at step740. It should be appreciated that while it may be advantageous todisable a POL regulator in light of a violation, the present inventionis not limited to such a result. For example, the system controller 102or a POL regulator may be programmed to perform a different action(e.g., closely monitor the faulty POL regulator, notify theadministrator, store fault-monitoring data, etc.) if a particularparameter violation occurs.

In another embodiment of the invention, the fault-monitoring data itselfindicates whether a monitored parameter violates a known parameter. Forexample, if output-current-set-point data (i.e., the highest desiredoutput current) is received as initial-configuration data and stored inthe storage device, the POL regulator (or more particular the POLcontroller 146) can provide the system controller 102 withfault-monitoring data that indicates whether the measured output currentis over or under the stored maximum current value. In this instance, ifthe received fault-monitoring data indicates that the output current isbelow the maximum value, the system controller 102 can continue tomonitor the POL regulator as previously described. Alternatively, if thereceived fault-monitoring data indicates that the output current isabove the maximum value, the system controller 102 (without making anyadditional calculations) can disable the POL regulator.

The POL control system 10 enables four different modes of operation. Inthe first operational mode, the POL regulators function independently inthe absence of a system controller and without interaction with otherPOL regulators. The POL regulators each include local feedback andcontrol systems to regulate their own performance as well as controlinterfaces to enable local programming. The POL regulators furtherinclude default settings in which they can revert to in the absence oflocal programming or data from the system controller. In other words,each of the POL regulators can operate as a standalone device withoutthe need for a system controller or interactions with another POLregulator.

In the second operational mode, the POL regulators interoperate for thepurpose of current sharing or interleaving in the absence of a systemcontroller. The POL regulators communicate with each other over thecurrent share interface. The synch/data line may be used to communicatesynchronization information to permit phase interleaving of the POLregulators, in which the phase is programmed locally by entering anaddress through hardwired connections. In either the first or secondmodes of operation, there would generally be information communicatedbetween the POL regulators except for synchronization; there would be noneed to communicate programming information.

In the third operational mode, the POL regulators operate as an array inwhich the behavior of each POL regulator and the array as a whole arecoordinated by a system controller. The system controller programs theoperation of each of the POL regulators over the synch/data serial bus,and thereby overrides the predetermined settings of the POL regulators.The synch/data serial bus is further used to communicate synchronizationinformation to permit synchronization and interleaving of the POLregulators. This operational mode would not include interdevicecommunications over the current share interface.

Lastly, the fourth operational mode includes both central control usingthe system controller and local control over certain functionality. Thisway, the POL regulators operate as an array coordinated by a systemcontroller and also interoperate with each other to perform functionssuch as current sharing.

It should be appreciated that the POL control system of the presentinvention provides a great deal of flexibility in the manner in which itimplemented to regulate power for a host system. FIG. 9 illustrates anexemplary embodiment of a POL control system implemented with a hostsystem. The host system may be a specialized master that provides themain interface to the user system CPU. Alternatively, the host systemmay be provided directly by the user system CPU or any other controlsystem dedicated to manage the power management subsystems.

One such embodiment would include a host system, a system controller andan array of POL regulators. An advantage of this embodiment is that thehost is relieved of the overhead of continuous communication with thePOL regulators. Instead, the system controller provides the supervisorylevel communications with the POL regulators, and the host may only beprovided with high level interactions, such as monitoring and statusinformation. The system controller also provides memory for storage ofPOL array programming parameters, thereby relieving the host of thisresponsibility. Another embodiment could include a system controller andarray of POL regulators, without a host system. The system controllerswould independently manage the operation of the POL control systemswithout need for interaction with a host. Alternatively, the host systemcould be adapted to provide the function of the system controller, andthereby would communicate directly with the array of POL regulators.While this would place substantial overhead requirements on the host, itmay be desirable in certain applications.

Specifically, the POL control system includes two separate POL controlsystems similar to that described above with respect to FIG. 3. Thefirst POL control system 220 (i.e., System A) includes a systemcontroller 225 coupled to a plurality of POL regulators 222, 224, 226,228. The second POL control system 210 has a similar structure,including a system controller and plurality of POL regulators. The POLcontrol systems may each be associated with different aspects of a hostsystem. For example, System A may provide regulated power to a firstrack of circuit boards, and System B may provide regulated power to asecond rack of circuit boards. Alternatively, Systems A and B may eachprovide regulated power to different circuit boards within one rack. Ineither case, by each having their own system controller, the POL controlsystems can operate autonomously from each other, and would therefore bebest suited for large host systems. It should be appreciated thatadditional POL control systems could be coupled to the host system, andthat two POL control systems are illustrated merely for convenience andsimplicity.

The system controllers from each the POL control systems wouldcommunicate with a host controller 240 via the user interface serialbus. As described above, the link with the host controller 240 enablesthe communication of monitoring, control and programming data. The hostcontroller 240 may additionally be coupled to a local area network (LAN)or wide area network (WAN). A user would then have several options foraccessing the POL control systems for purposes of monitoring,controlling and/or programming the POL control systems. In a firstembodiment, a user system 266 (i.e., computer) equipped with a suitableapplication programming interface (API) may be coupled directly to theuser interface bus for receiving communicating with the systemcontrollers of the Systems A and B. The user system would likely includea user interface, such as a graphical user interface (GUI), that enablesthe display of status information regarding the POL control systems. TheGUI may also serve as a diagnostic tool to enable troubleshooting offault conditions within the POL control system.

Alternatively, in a second embodiment, the user system 264 may insteadbe coupled directly to the host controller 240. This might enable thesame level of access to the POL control systems, or the host controller240 may limit the extent of access (e.g., monitoring only, withoutability to control or program). In yet another alternative, the usersystem 262 may be coupled to the host controller 240 through a LAN/WAN,thereby enabling the user to access the POL control systems from aremote location. As in the preceding embodiment, the host controller 240may limit the extent of access to the POL control systems.

FIG. 10 illustrates another exemplary embodiment of a POL control systemimplemented with a host system. The POL control system includes twoseparate POL control systems similar to that described above withrespect to FIG. 3. Unlike the embodiment of FIG. 9, the two POL controlsystem 320, 310 each include a plurality of POL regulators withoutseparate system controllers. Specifically, POL control system 320includes a plurality of POL regulators 322, 324, 326, 328. The secondPOL control system 310 has a similar structure. A system controller 330and front end regulator 332 may be included in a host system and providecontrol and intermediate bus voltage to each of the POL control systems.The system controller 330 may receive interrupt signals from each of thePOL control systems to thereby determine which system has control of thesynch/data bus. As before, the POL control systems may each beassociated with different aspects of a host system. For example, the POLcontrol systems A and B may each provide regulated power to differentcircuit boards within a common rack. Since the POL control systems sharea system controller, the POL control systems can be made to operatecooperatively with other, and would therefore be best suited for smallhost systems. It should be appreciated that additional POL controlsystems could be coupled to the host system, and that two POL controlsystems are illustrated merely for convenience and simplicity.

In this exemplary embodiment, the system controller 330 wouldcommunicate with a host via the user interface serial bus. Thecommunication with the host may be direct or via a local area network(LAN) or wide area network (WAN). A user may access the POL controlsystems for purposes of monitoring, controlling and/or programming thePOL control systems by coupling directly to the user interface bus. Asabove, the user system would likely include a user interface, such as agraphical user interface (GUI), that enables the display of statusinformation regarding the POL control systems.

A POL control system may be designed for a particular application, withcertain parameters and values selected to achieve desired performancerequirements. Once a set of desired parameters is achieved, theseparameters may be programmed into the system controller to enable massproduction of the POL array for use in a production level application.FIG. 11 shows an exemplary method of programming a POL array inaccordance with an embodiment of the invention, and FIGS. 12A-12Dillustrate a corresponding system implementing the exemplary method.

Specifically, in FIG. 12A, a prototype POL control system 830 includes aPOL array 832 and a system controller (unprogrammed) 834. A proxy host836 may also be provided to emulate interactions of the POL controlsystem with an actual host. An operator communicates with the prototypePOL control system using a suitable graphical user interface 838. Asshown in step 812, an initial arrangement of the POL array is defined bythe operator using the GUI 838. For example, the operator may designatethe number of POL regulators of the array, the output voltage parametersof the POL regulators, the fault monitoring characteristics, and othersuch parameters generally described above. In step 814, the operatorwill optimize the system by adjusting parameter values until a desiredconfiguration is achieved. For example, the GUI 838 may enable theoperator to simulate various operational loads, faults and otherconditions unique to the particular host environment, and can therebyselect operational parameters that are best suited to achieveperformance requirements of the host environment. When the operator issatisfied with the selected operational parameters, the GUI 838 wouldwrite these parameters to a suitable configuration file 840, as shown inFIG. 12B and in step 816.

Thereafter, the configuration file 84 would be used to program a finalsystem controller 852, as shown in FIG. 12C and step 818. This step maybe repeated many times to fabricate a production run of systemcontroller devices to be used in a production level application. Then, aproduction level POL control system 870 is produced including a POLarray 872 and a programmed system controller 852, for use with theactual host system 836, as shown in FIG. 12D. In step 820, thepre-programmed system controller devices are installed in an actualproduction system. Finally, at step 822, the POL control systemincluding the POL array 872 and system controller 852 are implemented inthe production system, and the system controller operates as describedabove to mange the operation of the POL array.

It should be appreciated that the POL control system of the presentinvention provides certain advantages over prior art distributed powerdistribution systems. The present POL control system requires much lesscomplexity or “glue” components (e.g., mediating devices) in order toprovide communication and control of a plurality of POL regulators,thereby reducing the amount of circuit board space for the POL controlsystem and number of control lines needed for communication, control andmonitoring. The POL control system is easily scalable by adding POLregulators to the array in order to support additional powerrequirements, without increasing the overhead requirements.

Having thus described a preferred embodiment of a method and system tocontrol and monitor an array of DC/DC power converters, it should beapparent to those skilled in the art that certain advantages of thesystem have been achieved. It should also be appreciated that variousmodifications, adaptations, and alternative embodiments thereof may bemade within the scope and spirit of the present invention. The inventionis further defined by the following claims.

1. A power control system for a host, comprising: a plurality ofprogrammable voltage regulators providing regulated power tocorresponding loads of the host; at least one serial data busoperatively connected to said plurality of programmable voltageregulators; and a system controller connected to said at least oneserial data bus and adapted to send and receive digital data to and fromsaid plurality of programmable voltage regulators, the system controllerhaving a host interface adapted for communications with the host via acommunication channel that is separate from said at least one serialdata bus; wherein, programming, control and monitoring information iscarried on said at least one serial data bus between said systemcontroller and said plurality of programmable voltage regulators, theprogramming, control and monitoring information being selectivelycommunicated between the system controller and the host via the hostinterface.
 2. The power control system of claim 1, wherein at least oneof the plurality of programmable voltage regulators comprises a DC-to-DCconverter.
 3. The power control system of claim 1, wherein said at leastone serial data bus further comprises a first data bus carrying saidprogramming, control and monitoring information between said systemcontroller and said plurality of programmable voltage regulators.
 4. Thepower control system of claim 3, wherein said at least one serial databus further comprises a second data bus carrying fault managementinformation between said system controller and said plurality ofprogrammable voltage regulators.
 5. The power control system of claim 1,further comprising a front-end regulator providing an intermediatevoltage to said plurality of programmable voltage regulators on anintermediate voltage bus.
 6. The power control system of claim 5,wherein said front-end regulator is combined with said system controllerin a single device.
 7. The power control system of claim 5, wherein saidplurality of programmable voltage regulators each further comprise apower conversion circuit adapted to transform said intermediate voltageto a desired output voltage.
 8. The power control system of claim 1,wherein each of said plurality of programmable voltage regulatorsfurther comprise an intradevice interface adapted to communicateinteraction information with at least one other one of said plurality ofprogrammable voltage regulators.
 9. The power control system of claim 8,wherein said interaction information further comprises current sharinginformation for a parallel operation between respective ones of saidplurality of programmable voltage regulators.
 10. The power controlsystem of claim 1, wherein said plurality of programmable voltageregulators each further comprise at least one serial interface adaptedto communicate with said at least one serial data bus.
 11. The powercontrol system of claim 10, wherein said plurality of programmablevoltage regulators each further comprises a hardwired interfacepermitting programming in the absence of data received from said systemcontroller via said serial interface.
 12. The power control system ofclaim 11, wherein said hardwired interface further comprises an inputenabling connection of at least one external resistor thereto to definean operating characteristic of a corresponding one of said plurality ofprogrammable voltage regulators.
 13. The power control system of claim11, wherein said hardwired interface further comprises an addressinterface adapted to receive a unique identification address for eachsaid programmable voltage regulator.
 14. The power control system ofclaim 11, wherein said hardwired interface further comprises a VIDinterface adapted to receive VID codes.
 15. The power control system ofclaim 1, wherein said plurality of programmable voltage regulators eachfurther comprises a memory containing default configuration settings torevert to in the absence of data received from said system controller.16. The power control system of claim 1, wherein the programminginformation comprises initial-configuration data defining desiredoperating parameters for at least one of the plurality of programmablevoltage regulators.
 17. The power control system of claim 16, whereinsaid plurality of programmable voltage regulators each further comprisesa memory adapted to store the initial-configuration data, eachprogrammable voltage regulator thereby operating in accordance with thestored initial-configuration data.
 18. The power control system of claim16, wherein the initial-configuration data includes at least outputvoltage set point data.
 19. The power control system of claim 16,wherein the initial-configuration data includes at least low-voltagelimit data.
 20. The power control system of claim 16, wherein theinitial-configuration data includes at least high-voltage limit data.21. The power control system of claim 16, wherein theinitial-configuration data includes at least output voltage slew ratedata.
 22. The power control system of claim 16, wherein theinitial-configuration data includes at least enable/disable data. 23.The power control system of claim 16, wherein the initial-configurationdata includes at least timing data.
 24. The power control system ofclaim 1, wherein the monitoring information comprises fault-monitoringdata defining status of at least one of the plurality of programmablevoltage regulators.
 25. The power control system of claim 24, whereinsaid plurality of programmable voltage regulators each further comprisesa memory adapted to store the fault-monitoring data for a respective oneof the programmable voltage regulators.
 26. The power control system ofclaim 24, wherein said fault-monitoring data comprises at least outputvoltage data.
 27. The power control system of claim 24, wherein saidfault-monitoring data comprises at least output current data.
 28. Thepower control system of claim 24, wherein said fault-monitoring datacomprises at least temperature data.
 29. The power control system ofclaim 1, wherein the system controller further comprises a memoryadapted to store the monitoring information.
 30. The power controlsystem of claim 1, wherein the system controller sends the commandinformation in response to the monitoring information.
 31. The powercontrol system of claim 30, wherein the command information includes acommand to disable a particular one of the plurality of programmablevoltage regulators.
 32. The power control system of claim 1, wherein thesystem controller notifies the host in response to the monitoringinformation.
 33. The power control system of claim 1, wherein the systemcontroller compares the monitoring information to predeterminedparameters to determine whether corrective action is needed.
 34. Thepower control system of claim 1, wherein each one of the plurality ofprogrammable voltage regulators includes a unique ID.
 35. The powercontrol system of claim 1, wherein the system controller sends a clocksignal on the serial data bus to synchronize communication of theprogramming, control and monitoring information.
 36. The power controlsystem of claim 1, wherein at least one of the programming, control andmonitoring information is communicated on the serial data bus in theform of a message having a command set, a data set, and an address set.37. The power control system of claim 1, further comprising a userinterface operable from the host for receiving communications from thesystem controller.
 38. The power control system of claim 37, wherein theuser interface further comprises a graphical user interface.
 39. Thepower control system of claim 38, wherein the graphical user interfaceprovides status information regarding the plurality of programmablevoltage regulators.
 40. The power control system of claim 38, whereinthe graphical user interface provides a diagnostic tool for evaluating afault condition of at least one of the plurality of programmable voltageregulators.
 41. The power control system of claim 37, wherein the userinterface communicates with the host interface through a local areanetwork.
 42. The power control system of claim 37, wherein the userinterface communicates with the host interface through a wide areanetwork.
 43. The power control system of claim 1, wherein at least oneof the plurality of programmable voltage regulators communicate themonitoring information with at least one other one of the programmablevoltage regulators.